In the prior art, a power tool capable of performing a reciprocative cutting action often incorporates a counterweight to reduce vibrations caused by the reciprocating movement. In U.S. Pat. No. 6,286,217, a counterweight is driven by a pivot arm to perform reciprocating movement to reduce the vibration of the reciprocating rod. This increases the length of the housing in an axial direction. Moreover this involves a number of moving parts and is difficult to manufacture.